Many internal combustion engines, whether compression ignition or spark ignition engines, use fuel injection systems to provide precise and reliable fuel delivery into the combustion chamber of the engine. Such precision and reliability are necessary to address the goals of improved fuel efficiency, maximum power output, and reduction of undesirable emissions. Generally, fuel systems will include a fuel pump and one or more fuel injectors. The fuel pump will supply fuel to the injectors, which will subsequently provide precise control of the fuel supply and timing to engine cylinders.
Traditionally, hard coatings can be applied to components of fuel systems to reduce wear and/or prevent corrosion. For example, where opposing parts contact one another, a coating may be used to reduce wear between the components by controlling friction and/or providing increased resistance to wear. However, it is generally believed that it is desirable to apply a coating to only one surface of opposing parts, while producing another opposing surface from a softer, uncoated metal (e.g., a steel substrate) or other material that is softer than the hard coating. In this way, the uncoated, softer material may be polished or reshaped by the opposing coating to produce a smooth surface and/or more desirable shape that results in a reduced overall wear rate.
In addition, whether using bare metal or coated components in fuel system components, the fuel system components may include specific geometries that control the surface area over which the components engage one another. For example, various valves, such as three-way valves, which are used in fuel injectors, include a valve body and valve seat against which the valve body rests. To prevent fluid flow through the valve, the valve body is pressed against the valve seat. In this configuration, the shapes of the valve body and valve seat affect the surface area and pressure exerted on the component materials. This in turn affects the performance of the valve and also may affect how the valve body and/or valve seat wear during use.
One prior art fuel system valve is disclosed in U.S. Pat. No. 6,173,912, which issued to Gottlieb et al. on Jan. 16, 2001 (hereinafter “the '912 patent”). The valve of the '912 patent includes a valve body having a valve seat and a valve plate. The valve plate abuts the valve seat in a closed condition, and a seal gap is formed in an open condition. The surfaces of the valve seat and valve plate are angled such that the cross-sectional area of the seal gap decreases in a direction of the flow of a liquid through the valve.
Although the valve seat and plate of the '912 patent may be suitable for some applications, the valve seat and plate of the '912 patent may have some drawbacks. For example, the valve plate and valve seat may be produced from materials that will produce unacceptably high wear rates in the use of certain newer fuels. Further, improved overall device performance may be achieved with newer materials selected for both components of the valve seat and plate. However, the use of hard coatings with the valve seat and plate of the '912 patent may produce unacceptably high wear rates because the valve and seat of the '912 patent may be configured such that the pressure between the valve and seat is localized to a small area. Further, when such a configuration is used with uncoated valve materials, or in valves in which only one of the valve seat or plate is coated, the uncoated materials may be deformed to allow the materials to be broken in, thereby producing a larger seat-to-plate contact area. However, when harder coatings are used, such coatings may not break in as readily, and therefore, it may be desirable to produce valve geometries that produce contact areas between a coated valve body and coated valve seat that will produce suitable control of fluid flow with coated components.
The disclosed valves aid in overcoming one or more of the aforementioned problems and the shortcomings of the related art solutions to such problems.